Switching from tankless coil to indirect?

Old 07-03-14, 09:55 PM
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Question Switching from tankless coil to indirect?

I'm new here. Been reading a lot of threads and already had a lot of questions answered. This is a very informative site. Thank you, for all that you do.
I'll start off by telling you what I've got;

1947 roughly 1500 sqft house with cathedral ceilings, and some upgrades, not super insulated, decent windows and doors (haven't done the heat loss calc. yet)
1977 The New Yorker boiler AP-790 154,000 BTUH with a tankless coil
Beckett oil burner AC-046132 running a .80 nozzle
HW TAR L8124A, C L8151A Set for summer hot water 130, 110, 20 / winter heating season usually 160, 130, 20
30lb. pressure relief valve
12-15 lb automatic feed
This runs 3 zones of a radiant heating system, copper in slab, mostly circa 1947/
with 1 zone, a small pathetic 1968 addition, having slant fin radiators and an uninsulated floor

On supply side, in this order:
Shutoff valve
B&G FOG200 Flo control valve
Taco 4900 series air separator (was having a problem with air) was told I probably have a leak in 1 of my floors ...);
Ancient expansion tank with a drain valve on the bottom
Pipes going out to 4 zones

On return side, in this order:
Pipes coming back from 4 zones
Each with;
shut off valve
drain valve
Taco valve 571-2
shutoff valve
All coming into 1 pipe with;
drain valve
shutoff valve
Taco circ pump 0011-F4
Back to the boiler

I've acquired a slightly used Boilermate WH7Z 40 gal. And hoping to save on fuel costs, I thought installing it would be a relatively easy job. A little plumbing, a few wires...
I downloaded the installation manual and a couple of things jumped out at me:

CAUTION! Be sure the return line is NOT plumbed to the suction side of any heating circulators. This may require moving the heating circulator off the boiler tapping on packaged boilers. Failure to do so will result in overheating and tank damage when the heating system is in operation.

A. Do I really have to move my circulator? It is too close to the boiler to make any connections between it and the boiler. And I know that flange is not coming off the nipple. Nor is the nipple coming out of the boiler. I tried when I replaced the pump 10 years ago. Fortunately it fit the new pump.

CAUTON! If a steel hydropneumatic tank is in place, AMTROL® recommends replacing it with a properly sized EXTROL® or Radiant EXTROL® expansion tank. Otherwise, significant heat transfer problems can occur by causing air to be trapped in the heat exchanger. If the boiler system has an EXTROL® or Radiant EXTROL® expansion tank and the boiler temperatures are being changed, resize the EXTROL® or Radiant EXTROL® expansion tank.

B. Do I have to replace my expansion tank too? This job is getting bigger!

WARNING! CALIFORNIA PROPOSITION 65 This product contains a chemical known by the State of California to cause cancer and birth defects or other reproductive harm. (California Installer/Contractor - California law requires that this notice be given to consumer/end user of this product.) For more information: www.amtrol.com/prop65

C. How bad does the plastic liner leach out chemicals at 130-140 degrees? Should I ditch it and spend a fortune on one with a ss tank? Or just keep my tankless coil and try to insulate and make the boiler more efficient? BTW I can't afford a ss tank or a new boiler. I could do some small upgrades though.

Now I looked around to see if these things were addressed anywhere, and could not find anything. But as I said I got a lot of other questions answered. and brought up some more.

1. I want to make it a priority system. I'll need a wiring diagram.
2. I want to make my boiler a cold start. Found your wiring diagram on that, thanks NJ Trooper.
3. What would the best settings be in my aquastat, when I'm done?
4. Having a dedicated circulator pump seems to be preferred. Taco 007 for me too?
5. Indirect will be 5 ft from boiler at same level. Would you recommend 3/4" or 1" piping for that?
6. The mechanical control on the boilermate seems to be preferred. I was given both, digital & mech. Simpler is probably best.
7. I hope to clean it out good before installing. Any suggestions?
8. I do have somewhat hard water. It tends to leave a light crust on things over time. I read the instructions for cleaning the coil in the manual. How often would you suggest doing that?
9. The Field Control OVD-6 oil vent damper sounded promising. Does it require a barometric damper installed upstream? I have nothing at all in my vent.
10. And lastly, the Heat Manager or Intellicon, would one of those help cut fuel costs in my situation? Which would adapt more easily?

I know I have asked a lot of questions, I need to get my head fully wrapped around this project before I start. And figure out what it's going to cost.
Let me know if you need pictures,
Thank you for your time,
You guys are great!
Old 07-04-14, 07:58 PM
Join Date: Nov 2011
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It's good that you are thinking things through. But I don't see how you can get around the basic piping requirements. The caution against plumbing the indirect tank return to the suction side of the boiler circulator is unambiguous.
Old 07-04-14, 09:36 PM
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Thank you Rockledge,
Could you explain to me why that setup would cause a tank to overheat? I have seen pictures of more than one indirect system, on this site, with the pumps plumbed on the return side. Nobody ever red flagged them. And I don't understand WHY it can't be done. Of course, in those pictures the indirects were a different brand than the one I've got. My tank has a plastic liner. But for all the trouble and expense it will be to move my circulator and change the expansion tank out. I'm not sure it's worth it. I might be better off just finding a different indirect. Or keeping my tankless and finding other ways to cut fuel costs. I don't have a ton of money to throw at this project. And the more I read, the bigger it gets. The warning about cancer and birth defects kind of turns me off too. I'm not sure I want to use that thing with potable water. I plan on doing a solar project in the future anyway, I may be able to utilize it then.
Old 07-05-14, 05:45 PM
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roughly 1500 sqft house
New Yorker boiler AP-790 154,000 BTUH
Good Grief Charlie Brown! Without doing a heat loss calc, I'm saying at LEAST TWICE what you need.

CAUTION! Be sure the return line is NOT plumbed to the suction side of any heating circulators. This may require moving the heating circulator off the boiler tapping on packaged boilers. Failure to do so will result in overheating and tank damage when the heating system is in operation.
The reason for this is because in that configuration the tank would be getting heated every time the boiler ran for a heat call. There would be no way to stop this with a check valve either, because the check valve would have to be in the direction of flow...

If you intend to use a zone valve for the boilermate, this should not be an issue, although a dedicated pump is optimal and preferred. Lots of them installed with zone valves though and they seem to work fine with no complaints.

If you are that concerned about the Prop 65 warning, you should contact Amtrol and ask for an MSDS sheet or some specification as to exactly what chemicals the warning refers to.

If it was THAT bad, they wouldn't be selling them. You know that CA is run by a bunch of liberal weenies that are afraid of their own shadows, right?
Old 07-18-14, 02:58 PM
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In directs need their own circ. I don't know why but plumbing code in Massachusetts requires it. As far as having the water heater on priority you can get a 4 zone switching relay with a priority zone. You need to pipe it like trooper said or it will over heat. Amtrol is a good brand and the coil inside is easily replaced if it were to leak. If you are coming here looking for piping and wiring diagrams I'd let a pro do it. It's easy to do but it sounds like you are in a little over your head.

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